1. Field of Invention
The present invention relates to a fan and a fan frame.
2. Related Art
Since the performances of electronic products have been improved, a heat dissipation device becomes one of the indispensable equipments for the electronic products. If the heat generated by the electronic product can not be dissipated properly, the performance may deteriorate and, even worse, the electronic product may be burnt out. Especially for the micro electronic devices such as the integrated circuits (ICs), the dissipation device is much more important. Because the integrated density of the ICs increases and the packaging technology progresses, the size of the ICs becomes smaller. Thus, the heat accumulated in per unit area becomes higher. Therefore, the heat dissipation device with high heat dissipation efficiency has become one of the most important development areas in the electronic industry.
A fan is the most popular heat dissipation device, as shown in FIGS. 1A and 1B, a fan frame 10 of a conventional axial-flow fan is a square structure. A base 12 is disposed in the main body 11 of the fan frame 10 and is adjacent to the outlet S. The base 12 is connected to the main body 11 through a plurality of ribs 13. In order to increase the outlet area for airflows, the main body 11 has several arc guiding angles R disposed around the outlet S. However, the square structure of the fan frame 10 has the geometrical limitation. That is, parts of the guiding angles R disposed at the side edges of the square structure will form several straight-cut lines P. In this case, the distance between the base 12 and the straight-cut line P is different from that between the base 12 and the guiding angle R. Thus, the variation of the area of the outlet S is too large, which may result in the large difference between the airflow speeds at the outlet S. This will cause the turbulence of the airflow at the outlet S and thus increase the noise.